Canada reports progress in avian flu battle

May 13, 2004 (CIDRAP News) – Canadian authorities reported progress yesterday in their battle to stamp out avian influenza in British Columbia, while news services reported possible signs of a new strain of avian flu virus in the outbreak area.

Canadian officials announced plans on Apr 5 to sacrifice about 19 million poultry in the Fraser River Valley near Vancouver to control an outbreak of highly pathogenic H7N3 avian flu. The disease has been detected in 40 commercial poultry farms and 10 backyard flocks.

Yesterday the Canadian Food Inspection Agency (CFIA) said the campaign to destroy all poultry within 3 kilometers of infected farms was nearing completion. A total of 296 backyard flocks had been destroyed, the agency said.

More than 500 sites have tested negative for avian flu, and no new infected farms have been found since Apr 29, the CFIA said. The agency said workers have begun cleaning and disinfecting 21 of the 40 infected farms.

Also yesterday, British Columbia officials they had found what may be a new strain of avian flu on a duck and goose farm at Abbotsford, B.C., in the outbreak area, according to an Associated Press (AP) report.

Dr. Perry Kendall, British Columbia medical health officer, said blood tests of geese and ducks revealed what looked like antibodies to an H5 avian flu virus, but the findings were not confirmed, according to the story. Confirmatory test results were expected tomorrow. The birds were not sick, the report said.

The recent widespread avian flu outbreaks in East Asia, which led to 24 fatal human cases and the sacrifice of millions of birds, involved an H5N1 virus. But Kendall said the absence of illness in the Canadian birds suggests the strain involved is not the same as in the Asian outbreaks.

The AP report said the finding of a possible new virus prompted officials to close a school across the road from the duck and goose farm. No children or staff members at the school had any signs of illness, said Sally Greenwood of the British Columbia Centre for Disease Control (BCCDC). She said the school would be closed until the end of the week and that plans called for destroying all the birds on the farm by then, according to the report.

The report quoted Rick Thiessen, president of the British Columbia Chicken Growers Association, as saying that 75% of the poultry in the outbreak area had been destroyed.

In other developments, a consortium of British Columbia medical agencies reported last week that they had sequenced the genome of the H7N3 virus involved in the outbreak.

"The genome sequencing demonstrated that this is entirely a bird isolate, and contains no human influenza A genes at this time," stated an announcement from the British Columbia Cancer Agency's Genome Sciences Center, the BCCDC, and the Animal Health Center of the Ministry of Agriculture, Food and Fisheries.

The project revealed a previously unknown mutation in the virus that could explain its increased virulence, the statement said.